Method for manufacturing an electronic module and electronic module

ABSTRACT

This publication discloses an electronic module, comprising a first conductive pattern layer and a first insulating-material layer on at least one surface of the first conductive pattern layer, at least one opening in the first insulating-material layer that extends through the first insulating-material layer, a component having a contact surface with contact terminals, the component being arranged at least partially within the opening with its contact terminals electrically coupled to the first conductive pattern layer, a second insulating-material layer provided on the first insulating-material layer, and a conductive pattern embedded between the first and second insulating material layers. This publication additionally discloses a method for manufacturing an electronic module.

RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/788,701, filed on Feb. 12, 2020, which is a Continuation of U.S.patent application Ser. No. 14/580,257, filed on Dec. 23, 2014, which isa Continuation-in-Part of U.S. patent application Ser. No. 10/572,340,filed on Sep. 15, 2004. The subject matter of which is incorporated byreference herein in its entirety.

FIELD OF THE INVENTION

Aspects of the present invention relate to an electronic module.

Further aspects of the present invention relate to a method formanufacturing an electronic module.

In particular, embodiments of the invention relate to an electronicmodule, in which one or more components are embedded in an installationbase. The electronic module being manufactured can be a module like acircuit board, which includes several components, which are connected toeach other electrically, through conducting structures manufactured inthe module. Embodiments of the invention relate to an electronic module,which contains microcircuits, to which several contact terminals areconnected. In addition to, or in place of microcircuits, othercomponents too, for example, passive components, can, of course, beembedded in the installation base. Thus, the intention is to embed inthe electronic module such components as are typically attached in anunpackaged form to the circuit board (to the surface of the circuitboard). Another important group of components are components that aretypically packaged for connection to a circuit board. The electronicmodules to which the invention relates can, of course, also includeother types of components.

BACKGROUND OF THE INVENTION

The installation base can be of a type similar to the bases that aregenerally used in the electronics industry as installation bases forelectrical components. The task of the base is to provide componentswith a mechanical attachment base and the necessary electricalconnections to both components that are on the base and those that areoutside the base. The installation base can be a circuit board, in whichcase the construction and method to which the invention relates areclosely related to the manufacturing technology of circuit boards. Theinstallation base may also be some other base, for example, a base usedin the packaging of a component or components, or a base for an entirefunctional module.

The manufacturing techniques used for circuit boards differ from thoseused for microcircuits in, among other things, the fact that theinstallation base in microcircuit manufacturing techniques, i.e. thesubstrate, is of a semiconductor material, whereas the base material ofan installation base for circuit boards is some form of insulatingmaterial. The manufacturing techniques for microcircuits are alsotypically considerably more expensive that the manufacturing techniquesfor circuit boards.

The constructions and manufacturing techniques for the cases andpackages of components, and particularly semiconductor components differfrom the construction and manufacture of circuit boards, in thatcomponent packaging is primarily intended to form a casing around thecomponent, which will protect the component mechanically and facilitatethe handling of the component. On the surface of the component, thereare connector parts, typically protrusions, which allow the packagedcomponent to be easily set in the correct position on the circuit boardand the desired connections to be made to it. In addition, inside thecomponent case, there are conductors, which connect the connector partsoutside the case to connection zones on the surface of the actualcomponent, and through which the component can be connected as desiredto its surroundings.

However, component cases manufactured using conventional technologydemand a considerable amount of space. As electronic devices have grownsmaller, there has been a trend to eliminate component cases, which takeup space, are not essential, and create unnecessary costs. Variousconstructions and methods have been developed to solve this problem,with the aid of which components can placed inside the circuit-boardstructure.

US patent publication 4 246 595 discloses one solution, in whichrecesses are formed in the installation base for the components. Thebottoms of the recesses are bordered by a two-layered insulation layer,in which holes are made for the connections of the component. The layerof the insulation layer that lies against the components is made of anadhesive. After this, the components are embedded in the recesses withtheir connection zones facing the bottom of the recess, electricalcontacts being formed to the components through the holes in theinsulation layer. If it is wished to make the structure mechanicallydurable, the component must also be attached to an installation base, sothat the method is quite complicated. It is extremely difficult to use acomplicated method, which demands several different materials andprocess stages, to profitably manufacture cheap products.

JP application publication 2001-53 447 discloses a second solution, inwhich a recess is made for the component in an installation base. Thecomponent is placed in the recess, with the component's contact areasfacing towards the surface of the installation base. Next, an insulationlayer is made on the surface of the installation base and over thecomponent. Contact openings for the component are made in the insulationlayer and electrical contacts are made to the component, through thecontact openings. In this method, considerable accuracy is demanded inmanufacturing the recess and setting the component in the recess, sothat the component will be correctly positioned, to ensure the successof the feed-throughs, relative to the width and thickness of theinstallation board.

International patent application publication WO 03/065778 discloses amethod, in which at least one conductive pattern is made in the base, asare through-holes for semiconductor components. After this, thesemiconductor components are placed in the holes, aligned relatively tothe conductive pattern. The semiconductor components are attached to thestructure of the base and one or more conductive-pattern layers aremanufactured in the base, in such a way that at least one conductivepattern forms an electrical contact with the contact areas on thesurface of the semiconductor component.

International patent application publication WO 03/065779 discloses amethod, in which through-holes are made in the base for semiconductorcomponents, in such a way that the holes extend between the first andsecond surfaces of the base. After the manufacture of the holes, apolymer film is spread over the second surface of the base structure, insuch a way that the polymer film also covers the through-holes made forthe semiconductor components, on the second side of the base structure.Before the hardening of the polymer film, or after its partialhardening, the semiconductor components are placed in the holes made inthe base, from the direction of the first surface of the base. Thesemiconductor components are pressed against the polymer film so thatthey adhere to the polymer film. After this, the final hardening of thepolymer film is performed and additional conductive-pattern layers aremanufactured, in such a way that at least one conductive pattern formsan electrical contact with the contact areas on the surface of thesemiconductor components.

SUMMARY OF THE INVENTION

It is an object of certain embodiments of the invention to provide anelectronic module. It is another object of certain embodiments of theinvention to create a simple and reliable method with low manufacturingcosts, for embedding components in an installation base.

Embodiments of the invention are based on commencing manufacture from aninsulating board, which is surfaced on at least one side with aconductive layer. After this, a recess or opening is made in theinsulation, which opens onto one surface of the board, but does notpenetrate the conductive layer on the opposite surface of the board. Acomponent is attached to the recess or opening and electrical contactsare formed between the conductive layer and the contact areas, orcontact protrusions of the component. After the attachment of thecomponent, conductive patterns are formed from this conductive layer,which become part of the circuit-board structure, or other electronicmodule. An additional conductive pattern is embedded in theinsulating-material of the module. According to one example, there is anelectronic module, comprising a first conductive pattern layer and afirst insulating-material layer on at least one surface of the firstconductive pattern layer, at least one opening in the firstinsulating-material layer that extends through the firstinsulating-material layer, a component having a contact surface withcontact terminals, the component being arranged at least partiallywithin the opening with its contact terminals electrically coupled tothe first conductive pattern layer, a second insulating-material layerprovided on the first insulating-material layer, and a conductivepattern embedded between the first and second insulating materiallayers.

Considerable advantages are gained with the aid of embodiments of theinvention. This is because embodiments of the invention can be used todesign a simple and reliable method with low manufacturing costs, whichcan be used to manufacture electronic modules containing embeddedcomponents. The conductively surfaced insulating board used as the basicmaterial is one of the basic raw materials of the circuit-board industryand boards of this kind are available cheaply and reliably. In themethod, the use of the raw material is extremely efficient, as theconductively surfaced insulating board is exploited to manufacture theconductive patterns of the electronic module. Even circuits that areembedded inside the insulating board can be connected electrically tothis conductive-pattern layer. An additional conductive pattern can beembedded in the insulating material of the board which can be connectedelectrically to the conductive-pattern layer. The embedded conductivepattern can be totally separated from the environment by means of theinsulating-material layers.

According to certain embodiments of the invention, at least one neutralbending axis of the electronic module can be in the middle of or insidethe embedded conductive pattern. Such a location of an embeddedconductive pattern in the electronic module can minimize the risk ofbreaking an embedded conductive pattern due to bending of the structureduring manufacturing steps of the electronic module at a later stage ordue to unintentional bending of the module as such after manufacture.This can improve reliability and lifetime of the embedded conductivepattern and the module as such.

The invention has embodiments, according to which relatively few processstages are required in the manufacturing process. Embodiments with fewerprocessing stages correspondingly also need less process equipment andvarious manufacturing methods. With the aid of such embodiments, in manycases it is also possible to reduce the manufacturing costs, compared tomore complicated processes.

The number of the conductive-pattern layers of the electronic module inaddition to the at least one embedded conductive pattern can also beselected according to the embodiments. There can be, for example, one ortwo conductive-pattern layers. In addition, additionalconductive-pattern layers can also be manufactured on top of them, inthe manner known in the circuit-board industry. There can thus be atotal of, for example, three, four, or five conductive-pattern layers ina module. In the very simplest embodiments, there is only a singleconductive-pattern layer, and, indeed, any conductive layer. In someembodiments, each of the conductive layers contained in an electronicmodule can be utilized to form conductive patterns.

There are also embodiments of the invention, in which conductivepatterns can be manufactured at the locations of the components. Thiswill increase the wiring capability of the structure, which, in turn,will permit the components to be placed closer together. The wiringcapability can also be improved by placing some of the components‘upside-down’, so that the active surfaces of components will face bothsurfaces of the board.

BRIEF DESCRIPTION OF THE FIGURES

For a more complete understanding of particular embodiments of thepresent invention and their advantages, reference is now made to thefollowing descriptions, taken in conjunction with the accompanyingdrawings. In the drawings:

FIGS. 1-17 show a series of cross-sections of an example of amanufacturing method of an electronic module.

FIGS. 18-27 show a series of cross-sections of another example of amanufacturing method of an electronic module.

FIGS. 28 and 29 show two intermediate stages of the manufacture of anelectronic module.

FIGS. 30 and 31 show two intermediate stages of the manufacture of anelectronic module in manufacturing methods according to certainembodiments of the present invention.

FIGS. 32 and 33 show two intermediate stages of the manufacture of anelectronic module in manufacturing methods according to certainembodiments of the present invention.

FIGS. 34 and 35 show two intermediate stages of the manufacture of anelectronic module in manufacturing methods according to certainembodiments of the present invention.

FIGS. 36, 37 and 38 show examples of patterned conductive layers fromthe conductive layers of FIGS. 31, 33 and 35 respectively.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

In the methods of the examples, manufacturing is started bymanufacturing an installation base of insulating material, which has aconductive layer on at least one surface. Typically, a commerciallyavailable sheet 1 of insulating material, both surfaces 1 a, 1 b ofwhich are surfaced with a conductive layer 4, is selected as theinstallation base. The insulating material 1 can be, for example,glass-fibre-reinforced epoxy (e.g., FR4). The conductive material 4 is,for its part, usually copper.

The installation base is typically selected in such a way that thethickness of the insulating material layer 1 is greater than thethickness of the components 6 to be later attached to the base, althoughthis is not essential. Recesses or openings 2, the size of which isselected according to the size of the components 6 being installed, aremanufactured by a suitable method in the insulating-material layer 1.The recesses or openings 2 are manufactured in such a way that theconductive layer 4 on the surface of the insulating material layer 1closes one or other end of the recess or opening 2. This is achieved,for example, by removing the conductive material 4 on the first surfaceof the installation base around the recess or opening 2. In connectionwith the removal of the conductive material 4, other patterns can alsobe formed in the conductive-pattern layer 4, for example, the patternsof the conductors of the circuit that will be formed. After this, themaking of recesses or openings 2 is continued using a suitable selectivemethod, which affects the insulating material 1 but not the conductivelayer 4. The recess or opening 2 thus manufactured should extend throughthe entire insulating material layer 1, while the conductive layer 4 atthe other end of the recess or opening 2 remains undamaged. Recesses oropenings 2 can be made in a corresponding manner from the directions ofboth surfaces.

Suitable alignment marks are also required to align the components 6,for the creation of which several different methods are available. Onepossible method is the making of small through-holes in the vicinity ofthe installation holes 2 of the components 6.

The components 6 are aligned in their installation holes 2 with the aidof the alignment holes or other alignment marks and the components areattached to the conductive layer 4. The components 6 can be attached tothe conductive layer 4 using a method that permits the formation of anelectrical contact between the conductive layer 4 and the contact areasof the component. Such methods are, for example, the ultrasonic bondingmethod, the thermo-compression method, and gluing with an electricallyconductive adhesive. Alternatively, it is possible to use a method, inwhich an electrical contact is formed between the conductive layer 4 andthe contact areas of the component. Such a method, is, for example,gluing with an insulating adhesive. In the following, the procedure ofthe process is described in greater detail, in connection with theattachment methods referred to above.

The term ultrasonic methods refers to a method, in which two piecescontaining metal are pressed together and vibration energy is brought tothe attachment area at an ultrasound frequency. The ultrasound and thepressure created between the surfaces being attached cause the piecesbeing attached to bond metallurgically to each other. Methods anddevices for creating ultrasound joints (ultrasonic bonding) arecommercially available. Ultrasonic bonding has the advantage that a hightemperature is not required to form the joint.

The term thermo-compression method refers to a method, in which twopieces containing metal are pressed against each other and thermalenergy is applied to the joint area. The thermal energy and the pressurecreated between the surfaces being attached cause the pieces beingattached to bond metallurgically to each other. Methods and devices formaking thermo-compressed joints (thermo-compression bonding) are alsocommercially available.

The term adhesive refers to a material, by means of which the componentscan be attached to the conductive layer. One property of the adhesive isthat the adhesive can be spread on the surface of the conductive layer,and/or of the component in a relatively fluid form, or otherwise in aform that will conform to the shape of the surface. Another property ofthe adhesive is that, after spreading, the adhesive hardens, or can behardened, at least partly, so that the adhesive will be able to hold thecomponent in place (relative to the conductive layer), at least untilthe component is secured to the structure in some other manner. A thirdproperty of the adhesive is its adhesive ability, i.e. its ability tostick to the surface being glued.

The term gluing refers to the attachment of the component and conductivelayer to each other with the aid of an adhesive. Thus, in gluing, anadhesive is brought between the component and the conductive layer andthe component is placed in a suitable position relative to theconductive layer, in which the adhesive is in contact with the componentand the conductive layer and at least partly fills the space between thecomponent and the conductive layer. After this, the adhesive is allowed(at least partly) to harden, or the adhesive is actively hardened (atleast partly), so that the component sticks to the conductive layer withthe aid of the adhesive. In some embodiments, the contact protrusions ofthe component may, during gluing, extend through the adhesive layer tomake contact with the conductive layer.

The components 6 can thus be attached to the surface of the conductivelayer 4 with the aid of an electrically conductive adhesive.Electrically conductive adhesives suitable for this purpose aregenerally available in two basic types: isotropically conductiveadhesives and anisotropically conductive adhesives. An isotropicallyconductive adhesive conducts in all directions, whereas ananisotropically conductive adhesive has a conductive direction and adirection diametrically opposite to this, in which the conductivity ofthe adhesive is extremely low. An anisotropically conductive adhesivecan be formed, for example, from an isolating adhesive, into whichsuitable conductor particles are mixed. If an anisotropically conductiveglue is used, the glue can be dosed over the component's entire surfacethat is being glued. When using an isotropically conductive glue, dosingshould be performed by area, so that short-circuits are not createdbetween the contact areas.

After the attachment of the components, the space remaining in theinstallation recess or opening 2 is typically filled with a filler 8.After this, the conductive layer 4 can be patterned, so that conductivepatterns 14 are formed, at least some of which are connected to thecontact areas of some of the components 6. After this, the process canbe continued by manufacturing additional conductive-pattern layers andmanufacturing the necessary through-holes.

Manufacturing exploiting the ultrasonic method and thethermo-compression method are disclosed in greater detail in the sameapplicant's Finnish patent application FI20030292, filed on 26 Feb.2003.

Manufacturing exploiting conductive glues are, in turn, disclosed ingreater detail in the same applicant's Finnish patent applicationFI20031201, filed on 26 Aug. 2003.

Thus, instead of attachment methods forming an electrical contact, it isalso possible to use methods, in which an electrical contact is notformed. Such a joint can be made, for example, by gluing the component 6to the surface of the conductive layer 4 with the aid of an insulatingadhesive. After gluing, the installation recess or opening 2 can befilled with a filler 8 and the feed-throughs made, through whichelectrical contacts can be formed between the contact areas of thecomponents 6 and the conductive layer 4. Holes 17 for the feed-throughsare made in the conductive layer 4, at the contact areas of thecomponents 6. The holes 17 are made in such a way that they also breakthrough the adhesive layer that has remained on top of the contactareas, or the contact protrusions. The holes 17 thus extend as far asthe material of the contact protrusions or other contact areas of thecomponents 6. The holes 17 can be made, for example, by drilling with alaser device, or by using some other suitable method. After this,conductive material is brought to the holes 17, in such a way that anelectrical contact is formed between the component 6 and the conductivelayer 4.

After this, the conductive layer 4 can be patterned, so that conductivepatterns 14 are formed, at least some of which are connected to some ofthe contact areas of the components 6. After this, the process can becontinued by manufacturing additional conductive-pattern layers andmanufacturing the necessary feed-throughs.

Manufacturing processes exploiting an insulating adhesive are disclosedin greater detail in the same applicant's Finnish patent applicationFI20030493, filed on 1 Apr. 2003.

The manufacturing processes according to the embodiments of theinvention can be implemented using manufacturing methods that aregenerally known to one versed in the art of manufacturing circuitboards.

In the following, the stages of the method shown in FIGS. 1-17 areexamined in greater detail.

Stage A (FIG. 1 ):

In stage A, a sheet of suitable insulating material 1, from which thebody of the installation base is formed, is selected for theelectronic-module manufacturing process. In the example using singleinsulating-material layer, the insulating-material layer 1 shouldpreferably be thicker that the component being installed. It will thenbe possible to embed the component entirely inside the installation baseand the electronic module will be smooth on both sides. Thicker specialcomponents, the rear surface of which will protrude beyond theinsulating-material layer 1, can, of course, also be embedded in theinstallation base. This is the preferred procedure particularly in suchexamples, in which several insulating-material layers are used, whichare joined together during the process. In that case, the components canbe embedded entirely in the structure, if the total thickness of theinsulating-material layer exceeds the thickness of the component. Onaccount of the durability of the structure, it is preferable for thecomponents in the finished electronic module to be located entirelyinside the installation base.

The insulating-material layer 1 can be, for example, a polymer base,such as a sheet of glass-fibre reinforced epoxy FR4. Other materialssuitable for the insulating-material layer 1 are PI (polyimide), FR5,aramid, polytetrafluoroethylene, Teflon®, LCP (liquid crystal polymer),and a pre-hardened binder layer, i.e. prepreg.

Prepeg refers to one of the basic materials of the circuit-boardindustry, which is generally a glass-fibre-reinforced insulating matsaturated with B-stage resin. A pre-hardened binder layer is typicallyused as a binding insulating material, when manufacturing multi-layercircuit-boards. Its B-stage resin is cross-bridged in a controlledmanner with the aid of temperature and pressure, for example, bypressing or laminating, so that the resin hardens and becomes C-stage.In the controlled hardening cycle, during the rise in temperature, theresin softens and its viscosity diminishes. Forced by the pressure, thefluid resin fills the holes and openings in its boundary surface. Whenusing a pre-hardened binder layer, this property is exploited to fillthe empty space remaining around the components. In this way, it ispossible to further simplify the electronic-module manufacturing methodsdescribed in the examples, as the installation recesses or openings forthe components need not be filled with a separate filler.

The insulating-material layer 1 is surfaced on both sides 1 a, 1 b, witha conductive layer 4, for example, a metal layer. The manufacturer ofthe electronic module can also select a ready surfaced insulating sheetas the basic material.

Stage B (FIG. 2 ):

In stage B, conductive patterns 14 are formed from the conductive layer4, using some suitable method. The removal of the conductive materialcan be performed, for example, using vaporization with a laser, or someselective etching method, which are widely used and well known in thecircuit-board industry. The conductive pattern 14 is made in such a waythat the surface of the insulating-material layer 1 is exposed at theinstallation recesses or openings 2 made for the components 6, or theside of the surface 1 a or 1 b. Correspondingly, the conductive materiallayer 14 on the opposite surface 1 a or 1 b of the insulating-materiallayer 1 is left intact.

Stage C (FIG. 3 ):

In stage C, suitably sized and shaped recesses or openings 2 are made inthe insulating-material layer 1, for the embedding of the components.The recesses or openings 2 can be made as required, using, for example,some known method used in circuit-board manufacture. The recesses oropenings 2 can be made, for example, using CO₂. The recesses or openings2 are made from the direction of the second surfaces 1 b and extendthrough the entire insulating-material layer 1, as far as the surface 1a of the conductive material layer 14 on the opposite surface of thelayer.

Stage D (FIG. 4 ):

In stage D, the blank of the electronic module is turned the other wayround.

Stage E (FIG. 5 ):

In stage E, additional installation recesses or openings 2 in theinsulating-material layer 1 are made for components in the direction ofthe first surface 1 a. Otherwise, the recesses or openings 2 can be madein the same way as in stage C.

Stage F (FIG. 6 ):

In stage F, an adhesive layer 5 is spread on the bottom of theinstallation recesses or openings 2, on top of the conductive layer 14.The thickness of the adhesive layer 5 is selected so that the adhesivesuitably fills the space between the component 6 and the conductivelayer 14, when the component 6 is later pressed onto the adhesive layer5. If the component 6 includes contact protrusions 7, it would be goodfor the thickness of the adhesive layer 5 to be greater, for exampleabout 1.5-10 times, the height of the contact protrusions, so that thespace between the component 6 and the conductive layer 4 will be wellfilled. The surface area of the adhesive layer 5 formed for thecomponent 6 can also be slightly larger than the corresponding surfacearea of the component 6, which will also help to avoid the risk ofinadequate filling.

Stage F can be modified in such a way that the adhesive layer 5 isspread on the attachment surfaces of the components 6, instead of on theattachment areas of the conductive layer 14. This can be carried out,for example, by dipping the component in adhesive, prior to setting itin place in electronic module. It is also possible to proceed byspreading the adhesive on both the attachment areas of the conductivelayer 14 and on the attachment surfaces of the components 6.

The adhesive used in this example is thus an electrical insulator, sothat the adhesive layer 5 itself does not form electrical contactsbetween the contact areas of the component 6.

Stage G (FIG. 7 ):

In stage G, the components 6 to be installed from the direction of thefirst surface 1 a are set in place in the electronic module. This can bedone, for example, by pressing the components 6 into the adhesive layer5, with the aid of an assembly machine.

Stage H (FIG. 8 ):

In stage H, the blank of the electronic module is turned the other wayround (see stage D).

Stage I (FIG. 8 ):

In stage I, an adhesive layer 5 is spread on the bottom of theinstallation recesses or openings 2 opening onto the second surface 1 b.Stage I is performed correspondingly to stage F, but from the directionof the opposite surface of the electronic module.

The work stages (e.g., stage F and I) made from opposite sides of theelectronic module can, in principle, also be performed simultaneously orconsecutively without turning the blank, if the manufacturing equipmentbeing used permits the work stages to be made from two directions.

Stage J (FIG. 9 ):

In stage J, the components 6 to be installed from the direction of thesecond surface 1 b are set in place, correspondingly to stage G of theelectronic module.

Stage K (FIG. 10 ):

In stage K, the space remaining between the components 6 and theinstallation base is filled entirely with a filler 8, which is, forexample, some suitable polymer. If the insulating material 1 is apre-hardened binder layer (prepreg), this stage can be omitted.

Stage L (FIG. 11 ):

In stage L, holes 17 are manufactured for the electrical contacts of thecomponents 6. The holes 17 are made through the conductive layer 14 andthe adhesive layer 5, in such a way that the material of the contactprotrusions, or the corresponding contact areas of the components 6 isexposed. The holes 17 can be made, for example, by drilling with the aidof a laser. A sufficient number of holes 17 is made at the contact areasof the components 6. If, in the process, it is intended to form directcontacts to the components 6 not only through the conductive layer 14,but also through some other conductive layer, the holes 17 need notnecessarily be made at contact area participating in such a contact.Typically, in order to form a reliable contact between the contact areasof a component 6 and, for example, a conductive layer 24, a hole 28 ismade in two parts; first a hole 17 is made between the component 6 andthe conductive layer 14 and then a hole 27 is made directly on top ofthis.

Stage M (FIG. 12 ):

In stage M, holes 11 are made in the module for the feed-throughs. Theholes 11 can be made, for example, mechanically by drilling.

Stage N (FIG. 13 ):

In stage N, conductive material 15 is grown into the holes 17 made instage L and into the through-holes 11 made in stage M. In the exampleprocess, the conductive material 15 is also grown elsewhere on top ofthe base, so that the thickness of the conductive layers 14 alsoincreases.

The conductive material 15 being grown can be, for example, copper, orsome other sufficiently electrically conductive material. In theselection of the conductive material 15, attention must be paid to theability of the material to form an electrical contact with the materialof the contact protrusions 7 or other contact areas of the component 6.In one example process, the conductive material 15 is mainly copper.Copper metallization can be made by surfacing the holes 11 and 17 with athin layer of chemical copper and after this the surfacing can becontinued using an electrochemical copper-growing method. Chemicalcopper is used, for example, because it will also form a surface on topof adhesive and will act as an electrical conductor in electrochemicalsurfacing. The growth of the metal can thus be performed using awet-chemical method, so that the growth is cheap.

Stage N is intended to form an electrical contact between the components6 and the conductive layer 14. In stage N, it is not essential toincrease the thickness of the conductive layer 14, instead the processcan be equally well designed in such a way that, in stage I, the holes17 and 11 are only filled with a suitable material. The conductive layer15 can be manufactured, for example, by filling the holes 17 and 11 withan electrically conductive paste, or by using some other metallizationmethod suitable for micro-feed-throughs.

In the later figures, the conductive layer 15 is shown merged with theconductive layer 14.

Stage O (FIG. 14 ):

In stage O, the conductive layers 14 are patterned in such a way thatconductive patterns 14 are formed on both surfaces of the sheet 1. Thepatterning can be performed, for example, in the manner described instage B.

After stage O, the electronic module contains a component 6 or severalcomponents 6, as well as conductive patterns 14, with the aid of whichthe component or components 6 can be connected to an external circuit orto each other. The preconditions then exist for manufacturing anoperational totality. The process can thus be designed in such a waythat the electronic module is ready after stage O and FIG. 14 indeedshows one possible electronic module. If desired, the process can alsobe continued after stage O, for example, by covering the electronicmodule with a protective substance, or by manufacturing additionalconductive-pattern layers on the first and/or second surface.

Stage P (FIG. 15 ):

In stage P, an insulating-material layer 21 is made on both surfaces ofthe sheet 1 as well as a conductive layer 24 on top of theinsulating-material layer 21. Stage P can be performed, for example, bypressing suitable RCF foils onto both surfaces of the sheet 1. The RCFfoil then includes both an insulating-material layer 21 and a conductivelayer 24. When the RCF foils are pressed onto the sheet 1 with the aidof heat and pressure, the polymer of the layer 21 forms a unified andtight insulating-material layer between the conductive layer 14 and 24.By means of this procedure, the conductive layer 24 too becomes quiteflat and smooth.

Stage Q (FIG. 16 ):

In stage Q, holes 27 are made for forming feed-throughs between theconductive layer 14 and 24. The holes can be made, for example, as instage L using a laser. In some examples, it is also possible to makeholes 28, with the aid of which a straight feed-through can be formedwith the conductive layer 24 and the contact protrusion or contact areaof the component 6.

Stage R (FIG. 17 ):

In stage R, conductive material 15 is grown in the holes 27 (and theholes 28) while at the same time the thickness of the conductive layer24 can also be increased. Stage R can be performed correspondingly toStage N.

After stage R, the process can be continued by patterning the conductivelayers 24 and possibly by manufacturing additional conductive layers oneither or both of the surfaces. Separate components can also beconnected to the conductive layer on the surface of the electronicmodule, in the conventional manner of circuit-board technology.

The following will deal, with the aid of FIGS. 18-27 , with somepossible modifications of the manufacturing process.

Stage A2 (FIG. 18 ):

In stage A2, as in stage A, a suitable insulating-material sheet 1, fromwhich the body of the installation base is formed, is selected for themanufacturing process of the electronic module. In the example process,the insulating-material layer 1 is surfaced from the first surface 1 awith a conductive layer 4, for example, a metal layer.

Stage B2 (FIG. 19 ):

In stage B2, as in stage C, suitably sized and shaped recesses oropenings 2 are manufactured in the insulating-material layer 1, for thecomponents to be embedded in the sheet. The recesses or openings 2 aremade from the direction of the second surface 1 b and extend through theentire insulating-material layer 1 as far as the surface of theconductive-material layer 4 on the opposite surface of the layer.

Stage C2 (FIG. 20 ):

In stage C2, the components 6 to be installed from the direction of thesecond surface 1 b are set in place in the recesses or openings 2 andconnected to the conductive layer 4. Electrical contacts are then alsoformed between the contact protrusions or contact areas of thecomponents and the conductive layer 4. The connection of the components6 can be made, for example, by gluing with an isotropically oranisotropically electrically conductive adhesive. The attachment canalso be performed using some other applicable method, for example, theultrasonic or thermo-compression method.

Stage D2 (FIG. 20 ):

In stage D2, the space remaining between the component 6 and theinstallation base is entirely filled with a filler 8, which is, forexample, some suitable polymer.

Stage E2, (FIG. 21 ):

In stage E2, conductive patterns 14 are formed from the conductive layer4, using some suitable method. The removal of the conductive materialcan be performed, for example, by vaporization with a laser, or usingone of the selective etching methods, which are widely using and wellknown in the circuit-board industry.

Stage F2 (FIG. 22 ):

In stage F2, a conductive layer 9 is formed on the second surface 1 b ofthe sheet 1. Stage F2 can be performed, for example, by laminating anRCF-foil onto the second surface 1 b.

Stage G2 (FIG. 23 ):

In stage G2, recesses or openings 2 for components are made in theinsulating-material layer 1, as in stage B2. Now the recesses openings 2are manufactured from the direction of the first surface 1 a and extendas far as the surface of the conductive-material layer 9.

Stage H2 (FIG. 24 ):

In stage H2, the components 6 to be installed from the direction of thefirst surface 1 a are connected to the conductive layer 9. The stage canbe performed as in stage C2.

Stage I2 (FIG. 20 ):

In stage I2, the space remaining between the components 6 and theinstallation base is entirely filled with a filler 8, which is, forexample, some suitable polymer.

Stage J2 (FIG. 25 ):

In stage J2, conductive patterns 19 are formed from the conductive layer9, using a suitable method.

Stage K2 (FIG. 26 ):

In stage K2, holes 27 are made to form feed-throughs between theconductive-pattern layers 14 and 19.

Stage L2 (FIG. 27 ):

In stage L2, conductive material is grown in the holes 27. Stage L2 canbe performed correspondingly as stage N.

After stage L2, the electronic module includes two conductive-patternlayers and embedded components 6 connected to them. If severalconductive layers are not required in the electronic module beingmanufactured, the module can, for example, be protected with aprotective substance after stage L2. After stage L2, it is alsopossible, if wished, to manufacture additional conductive layers in themodule, or to connect surface-assembled components to it. The modulescan also be connected to each other to create a multi-layer structure.

The above descriptions are of -examples, in which theinsulating-material layer 1 is formed from a single unifiedinsulating-material sheet, for example, a glass-fibre-reinforced epoxysheet, or a prepreg sheet. However, the insulating-material layer 1 canequally well be manufactured from more than one part. It is then alsopossible to proceed in such a way that the insulating-material layer 1is formed of more than one insulating material. FIGS. 28-31 shows twosuch examples.

FIG. 28 shows an element, which includes a first insulating-materiallayer 1, with components 6 set in recesses or openings made in it. Inaddition, the element includes a conductive layer 4 on the surface ofthe insulating-material layer 1. The thickness of the firstinsulating-material layer 1 is preferably greater than the height of thecomponents 6. An element like that shown in the figure can bemanufactured, for example, by combining the sub-processes of theprevious series of figures. In addition to the element, the figures alsoshow a second insulating-material layer 11, in which recesses oropenings 22 for components 6, as well as a second conductive layer 9 arealso made.

In the above example, the second insulating-material layer 11 isprepreg. The first insulating-material layer 1 can then also be of someother insulating material, for example, a glass-fibre-reinforced epoxysheet. After this, the layers are joined together, resulting in theelement depicted in FIG. 29 . As can be seen from FIG. 28 , the resincontained in the prepreg fills the space between the component 6 and itssurroundings. After this, the manufacture of the electronic module canbe continued with the aid of the sub-processes described above.

In the following, stages of the manufacture of an electronic module inmanufacturing methods according to certain embodiments of the presentinvention are examined in greater detail in FIGS. 30-35 . Features ofthe manufacturing methods described above can also be used in themanufacturing methods described below.

In FIGS. 30 and 31 two intermediate stages of the manufacture of anelectronic module in manufacturing methods according to certainembodiments of the present invention are illustrated. FIG. 30 shows afirst and a second element, both of which include a firstinsulating-material layer 1 and components 6 in recesses or openingsmanufactured in the insulating-material layer 1. In addition, theelements include conductive layers 4 on the first surfaces of theinsulating-material layers 1 and conductive patterns 19 on the secondsurfaces of the insulating-material layers 1. The conductive patterns 19are each located on the level of the respective components 6. In bothelements, the thickness of the first insulating-material layer isgreater than the height of the components 6. The second element isrotated relative to the first element in such a way that the conductivepatterns 19 face each other and a second insulating-material layer 11,in which recesses 22 or openings are also made for components 6, isplaced between the elements. After this, the elements are attached toeach other, resulting in the module structure shown in FIG. 31 . Thestructure of FIG. 31 is compact and thin, and, at this stage of theprocess, it already includes four conductive layers (layers 4, 4, 19,and 19). The conductive layers 19 are each located on the level of arespective component 6. The conductive layers 19 are embedded ininsulating material of the structure. Feed throughs or so called viaopenings, which are not shown in FIGS. 30 and 31 , are typically made inthe first insulating material layers 1 and electrical contacts aresubsequently formed between the conductive patterns 19 and the firstconductive layers 4. High-quality electrical contacts can be made, forexample, by forming a metallurgical connection by growing the conductormaterial chemically or by an electrochemical method. Another option isto grow a thin layer by a chemical method and continue the growing usinga cheaper electrochemical method. Of course, any other suitable methodcan be used instead or in addition to the aforementioned methods. Thus,the possible methods include, for example, electrochemical plating,chemical deposition methods, sputtering and vaporization. The contactstructure can include one, two or several layers of one, two or severalmetals. Possible metals include, but are not limited to, aluminum,copper, zinc, nickel, gold, titanium and iron, for instance. Alsoconducting adhesive, conductive paste or solder can be used, forinstance.

In the embodiment shown in FIGS. 30 and 31 too, prepreg can be used asthe second insulating-material layer 11. The first insulating-materiallayer 1 of both elements can then also be some other insulatingmaterial, for example, a glass-fibre-reinforced epoxy sheet. With theaid of the prepreg, excellent filling is achieved in the space betweenthe elements, as shown in the example of FIG. 29 . The modules shown inFIGS. 30 and 31 can be made, for example, with the aid of thesub-processes described above. The manufacture of the electronic modulecan also be continued in a corresponding manner as, for example, that ofthe elements shown in FIG. 10 or FIG. 24 , making allowance for theselected connection techniques, the patterning requirement of theconductive layers 4, and other similar special requirements of theprocess.

In FIGS. 32 and 33 two intermediate stages of the manufacture of anelectronic module in manufacturing methods according to certainembodiments of the present invention are illustrated. In FIG. 32 a firstinsulating-material layer 1 is provided on one surface of a firstconductive layer 4. Subsequently, two openings are made in the firstinsulating-material layer 1 that extend through the firstinsulating-material layer 1 as far as the first conductive layer 4. Twocomponents 6 having a contact surface, i.e. a first surface 31 withcontact areas or contact protrusions, are then placed in the openingswith their contact surfaces facing the first conductive layer 4 andattached to the conductive layer 4. A portion of the firstinsulating-material layer 1 can be between at least a portion of thecomponent and the conductor layer. Additionally, an insulating materialwhich is either the same or different from the insulating material ofthe first insulating-material layer 1 can be between at least a portionof the component and the conductor layer. Vias, for example, can beformed in the insulating material between contact surface(s) of thecomponent and the conductive layer.

A conductive pattern 19 can be made from conductor material on the firstinsulating-material layer 1. The conductive pattern 19 is located on thesame level as the component 6. Further, a second insulating-materiallayer 11 is provided on the first insulating-material layer 1 and theconductive pattern 19 such that the components 6 and the conductivepattern 19 are embedded in the first and second insulating-materiallayers 1, 11. Additionally, a second or third conductive layer 9 can beprovided on the second insulating-material layer 11.

The distance between a first surface 29 of the embedded conductivepattern 19 and the second conductive layer 9 in a directionperpendicular to the surface of the first conductive layer 4 is lessthan the distance between a first surface 31 of the component 6 and thesecond conductive layer 9. The first surface 29 of the embeddedconductive pattern 19, the first surface 31 of the component 6, and thesecond conductive layer 9 are arranged substantially parallel to eachother. The first surface 29 of the embedded conductive pattern 19 andthe first surface 31 of the component 6 are facing towards the firstconductive layer 4. The first conductive layer 4 is arrangedsubstantially parallel to the second conductive layer 9. The distancebetween a second surface 30 of the embedded conductive pattern 19 andthe first conductive layer 4 in a direction perpendicular to the surfaceof the first conductive layer 4 is also less than the distance betweenthe second surface 32 of the component 6 and the first conductive layer4. The second surface 30 of the embedded conductive pattern 19, thesecond surface 32 of the component 6, and the first conductive layer 4are also arranged substantially parallel to each other. The secondsurface 30 of the embedded conductive pattern 19 and the second surface32 of the component 6 are facing towards the second conductive layer 9.In other words, the embedded conductive pattern 19 is substantiallylocated on the same level as the component 6, but the height of theembedded conductive pattern 19 is less than the height of the component6. The height of the embedded conductive pattern 19 is defined as thedistance between the first surface 29 of the embedded conductive pattern19 and the second surface 30 of the embedded conductive pattern 19 in adirection perpendicular to the surface of the first conductive layer 4.The height of the component 6 is defined as the distance between thefirst surface 31 of the component 6 and the second surface 32 of thecomponent 6 in a direction perpendicular to the surface of the firstconductive layer 4.

According to certain embodiments, the second insulating-material layer11 can be made of a different material than the firstinsulating-material layer 1. One example is that the firstinsulating-material 1 layer can be a glass-fibre reinforced epoxy sheetand the second insulating-material layer 11 can be prepreg. Otherexamples of materials of the first and/or second insulating material arepolyimide, polyimide based materials, epoxies with or without fillers(e.g. fillers which are ceramic particles), epoxy based materials,non-glass fiber containing materials or combinations thereof.

According to certain examples, the material of the first insulatingmaterial layer 1 and/or the material of the second insulating materiallayer 11 can be materially different before and after manufacturing. Forexample, a pre-final product can have a first insulating material layer1 made from a polyimide film and the second insulating material layer 11can be made from an unfilled epoxy. During a curing process ofmanufacturing after the first and second insulating material layers havebeen placed in contact with one another, the polyimide of the firstinsulating material layer 1 will generally hold its form but theunfilled epoxy of the second insulating material layer will flow. In acase where both materials of the first and second insulating materiallayers would be effected by a manufacturing step, a final product mayhave only one combined insulating material layer, or an additionalinsulating material layer which is a combination of at least a portionof both first and second initial insulating material layers.

The embedded conductive pattern 19 is made of conductor material suchas, for example, copper, aluminum, zinc, nickel, gold, titanium or iron,a combination of two or more of the afore-mentioned metals, or any othersuitable conductive material. Also the first and second conductivelayers 4, 9 are made of conductor material such as, for example, copper,aluminum, zinc, nickel, gold, titanium or iron, a combination of two ormore of the afore-mentioned metals, or any other suitable conductivematerial.

After this, the layers are joined together, resulting in the elementdepicted in FIG. 33 . As can be seen from FIG. 32 , the resin containedin the prepreg fills the space between the component 6 and itssurroundings. After this, the manufacture of the electronic module canbe continued with the aid of the sub-processes described above.

In the final electronic module, e.g. after the manufacturing process, anembedded conductive pattern 19 is arranged such that it is separatedfrom the environment. At least one of the first and second conductivelayers 4, 9 will be further formed as conductive pattern layers.Additionally, feed throughs are provided in the first or secondinsulating material layer and an electrical contact is formed betweenthe embedded conductive pattern and the first or second conductivepattern layer.

In FIGS. 34 and 35 two intermediate stages of the manufacture of anelectronic module in manufacturing methods according to certainembodiments of the present invention are illustrated. In FIG. 34 a firstinsulating-material layer 1 is provided on one surface of a firstconductive layer 4. Subsequently, at least one opening is made in thefirst insulating-material layer 1 that extends through the firstinsulating-material layer 1 as far as the first conductive layer 4. Atleast one component 6 having a contact surface, i.e. a first surface 31with contact areas or contact protrusions, is then placed in the openingwith its contact surfaces facing the first conductive layer 4 andattached to the conductive layer 4. A conductive pattern 19 is made fromconductor material on the first insulating-material layer 1. Theconductive pattern 19 is located on the same level as the component 6.Further, a second insulating-material layer 11 is provided on the firstinsulating-material layer 1 and the conductive pattern 19 such that thecomponents 6 and the conductive pattern 19 are embedded in the first andsecond insulating-material layers 1, 11. Additionally, a secondconductive layer 9 is provided on the second insulating-material layer11.

After this, the layers can be joined together, resulting in an elementas depicted in FIG. 35 . The first and second insulating-material layers1, 11 can be of the same material, though they may be different and/orhave together formed one or more additional combined layers during amanufacturing process as discussed above. Further, the height of theembedded conductive pattern 19 is greater than in the previousembodiments. Additionally, the distance between a first surface 29 ofthe embedded conductive pattern 19 and the first conductive layer 4 in adirection perpendicular to the surface of the first conductive layer 4substantially equals a distance between a second surface 30 of theembedded conductive pattern 19 and the second conductive layer 9.

According to other embodiments, the distance between the second surface30 of the embedded conductive pattern 19 and the first conductive layer4 in a direction perpendicular to the surface of the first conductivelayer 4 substantially equals or equals the distance between the secondsurface 32 of the component 6 and the first conductive layer 4.

In further embodiments, the distance between the first surface 29 of theembedded conductive pattern 19 and the second conductive layer 9 in adirection perpendicular to the surface of the first conductive layer 4substantially equals or equals the distance between the first surface 31of the component 6 and the second conductive layer 9.

In certain embodiments, the height of the embedded conductive pattern 19substantially equals the height of the component 6. In other certainembodiments, the height of the embedded conductive pattern 19 is greateror less than the height of the component 6.

In case that the beam theory is applied to a cross-sectional portion ofthe electronic module, the neutral bending axis of the electronic moduleis located in the middle of the embedded conductive pattern 19 accordingto certain embodiments, thus minimizing the risk of breaking theembedded conductive pattern 19 due to bending of the structure duringmanufacturing steps of the electronic module at a later stage or due tounintentional bending of the module as such after manufacture. Accordingto certain other embodiments, the neutral bending axis of the embeddedconductive pattern 19 is located inside the embedded conductive pattern19. According to certain embodiments, the neutral bending axis islocated inside of at least a portion of the embedded conductive pattern19 or located totally outside of the embedded conductive pattern 19.

In the final electronic module, i.e. after the manufacturing process, anembedded conductive pattern 19 is arranged such that it is separatedfrom the environment. At least one of the first and second conductivelayers 4, 9 will be further formed as conductive pattern layers.Additionally, feed throughs are provided in the first or secondinsulating material layer and an electrical contact is formed betweenthe embedded conductive pattern and the first or second conductivepattern layer.

The embodiments of the previous figure series show some possibleprocesses, with the aid of which the invention can be exploited. Theinvention is not, however, restricted to only the processes disclosedabove, but instead the invention also covers other different processesand their end products, taking into account the full scope andequivalence interpretation of the Claims. The invention is also notrestricted to the constructions and methods described in theembodiments, it being obvious to one versed in the art that variousapplications of our invention can be used to manufacture very manydifferent electronic modules and circuit boards, which differ from theembodiments described above to even a great extent. The components andconnections of the figures are thus presented only to illustrate themanufacturing process. Thus, a great many alterations can be made to theprocess of the embodiments given above, without, however, deviating fromthe basic idea according to the invention. The alterations can relate,for example, to the manufacturing techniques described in the differentstages, or to the mutual sequence of the process stages.

In the processes described above, it is possible, for example, to useseveral techniques for attaching the components, for example, in such away that the components to be attached from the direction of the firstsurface are attached using some first technique and the components to beattached from the direction of the second surface are attached usingsome second technique, which differs from the said first technique.

In the embodiments given above, electronic modules are manufactured,which include components embedded from a first and a second direction.Of course, within the scope of the invention, it is also possible tomanufacture such simpler modules, which include only components embeddedfrom one direction. With the aid of such simpler modules, it is alsopossible to manufacture a module including components embedded in twodirections. The module can be manufactured, for example, in such a waythat two modules are laminated together from their ‘back’ sides, so thatthe active surfaces contained in the sub-modules face the oppositeoutward surface of the module that has been laminated together. Theembodiments according to the invention include at least one embeddedconductive pattern. The embodiments according to the invention mayinclude one or more embedded conductive patterns, e.g. in case that thecomponents are embedded from a first and a second direction.

Although the present invention has been described in detail for thepurpose of illustration, various changes and modifications can be madewithin the scope of the claims. In addition, it is to be understood thatthe present disclosure contemplates that, to the extent possible, one ormore features of any embodiment may be combined with one or morefeatures of any other embodiment.

It is to be understood that the embodiments of the invention disclosedare not limited to the particular structures, process steps, ormaterials disclosed herein, but are extended to equivalents thereof aswould be recognized by those ordinarily skilled in the relevant arts. Itshould also be understood that terminology employed herein is used forthe purpose of describing particular embodiments only and is notintended to be limiting.

The invention claimed is:
 1. An electronic module, comprising: a firstconductive pattern layer, and a first insulating-material layer arrangedon at least one surface of the first conductive pattern layer; at leastone opening in the first insulating-material layer that extends throughthe first insulating-material layer; a component comprising contactterminals, the component being arranged at least partially within the atleast one opening, the contact terminals electrically connected to thefirst conductive pattern layer; a second insulating-material layerdisposed on the first insulating-material layer; and a second conductivepattern layer spaced apart from the first conductive pattern layer by atleast the first and second insulating-material layers, wherein the firstconductive pattern layer and the second conductive pattern layer areeach substantially planar.
 2. The electronic module of claim 1, whereinthe second insulating-material layer directly contacts the component. 3.The electronic module of claim 1, wherein the second conductive patternlayer is spaced apart from the first conductive pattern layer by thecomponent.
 4. The electronic module of claim 3, wherein the secondconductive pattern layer is spaced apart from the component by thesecond insulating-material layer.
 5. The electronic module of claim 4,wherein the second insulating-material layer is continuously disposedbetween the second conductive pattern layer and the component.
 6. Theelectronic module of claim 1, wherein the first insulating-materiallayer is spaced apart from the component.
 7. The electronic module ofclaim 1, wherein the first insulating-material layer comprises adifferent material than a material of the second insulating-materiallayer.
 8. An electronic module, comprising: a first conductive patternlayer, and a first insulating-material layer arranged on at least onesurface of the first conductive pattern layer; an opening in the firstinsulating-material layer that extends through the firstinsulating-material layer; a component comprising contact terminals, thecomponent being arranged at least partially within the opening, thecontact terminals electrically connected to the first conductive patternlayer; a second insulating-material layer disposed on the firstinsulating-material layer; a third insulating-material layer disposed onthe second insulating-material layer; and a second conductive patternlayer spaced apart from the first conductive pattern layer by at leastthe first, second, and third insulating-material layers, wherein thefirst conductive pattern layer and the second conductive pattern layerare each substantially planar.
 9. The electronic module of claim 8,wherein the second insulating-material layer directly contacts thecomponent.
 10. The electronic module of claim 8, wherein the secondconductive pattern layer is spaced apart from the first conductivepattern layer by the component.
 11. The electronic module of claim 10,wherein the second conductive pattern layer is spaced apart from thecomponent by the second and third insulating-material layers.
 12. Theelectronic module of claim 11, wherein the second insulating-materiallayer is continuously disposed between the second conductive patternlayer and the component.
 13. The electronic module of claim 8, whereinthe first and third insulating-material layers are spaced apart from thecomponent.
 14. The electronic module of claim 8, wherein the first andthird insulating-material layers comprise a first material, the secondinsulating-material layer comprises a second material, the firstmaterial being different than the second material.